Field
The present disclosure relates to a fuel cell stack.
Related Art
A plurality of manifolds are formed inside of a fuel cell stack configured such that a stacked body of a plurality of unit cells stacked in a stacking direction is placed between a pair of terminal plates and a pair of end plates provided on respective sides thereof, are arranged parallel to the stacking direction and are configured to supply reactive gases to the respective unit cells, discharge off gases from the respective unit cells, and supply and discharge a cooling medium to and from the respective unit cells. A plurality of through holes are formed in at least one of the end plates such as to communicate with the plurality of manifolds formed inside of the fuel cell stack. In general, the end plate is made of a metal such as an aluminum alloy. One proposed technique forms a resin layer to cover a contact surface between the end plate and the terminal plate and inner circumferential walls of the through holes formed in the end plate, with a view to suppressing reduction of the insulating property and the corrosion resistance due to, for example, any of the reactive gases and the cooling medium (as described in JP 2015-8086A).
According to a configuration of the fuel cell stack, the stacked body of the unit cells may be placed in a case. In this configuration, an end face of the entire case and an end face of the stacked body placed in the case are covered by an end plate, and the outer periphery of the case and the end plate are fastened to each other by means of bolts or the like. With a view to ensuring the air tightness and the water tightness at a contact surface between the end plate and the case, a seal member such as a gasket is placed on the contact surface between the end plate and the case.
A difference in coefficient of thermal expansion between the end plate and the resin layer formed to cover the inner circumferential walls of the through holes formed in the end plate and the like may cause a gap between the resin layer and the end plate in the course of repeated operations of the fuel cell stack. Water is thus likely to enter into the case from a non-sealed portion of the contact surface between the end plate and the case where the seal member is not placed, a non-covered portion of the end plate that is not covered by the resin layer, or an outer circumferential edge of the resin layer. There is accordingly a demand for a technique that suppresses water from entering into a case in a contact surface between an end plate and a case.